A consideration in the design of consumer products is the use of a rechargeable battery to provide adequate, reliable, and unconstrained power to a consumer device. Up until about 20 years ago, most electrically powered consumer devices were simply coupled to the utility power grid. Rechargeable batteries saw limited use because earlier battery technology allowed only a very limited number of charging cycles with limited charging efficiency.
With the adoption of lithium-based batteries that allow for a large number of charge/discharge cycles, rechargeable batteries began to see increasing use for consumer electronics applications, facilitating the proliferation of electronic devices without tethering to the utility grid. Despite the great advantage of allowing consumers to use electronic devices such as cellular phones, tablets, and laptop computers, the battery operated electronic devices still needed to be connected to the utility grid to recharge the batteries.
In recent years, wireless power systems have been developed that allow recharging of the batteries without making a physical connection between the battery and the charger. The wireless power systems use resonant operation to transfer power from a charger to a battery. The battery itself is electrically/metallically tied to the load it will eventually power and charging is accomplished through a metallically isolated wireless interface. There are many reasons that the battery has been electrically/metallically tied to the load it operates including that both power transfer and communication in standard wireless interfaces is set up to allow transfer of power in only one direction. Additionally, standard wireless power interfaces are inefficient, so too much battery life would be lost by driving an electronic device through a wireless interface.
Standard wireless interfaces also require post regulators such as linear regulators because the control loop through a wireless interface is too slow for the wireless battery interface to adequately regulate the output of the battery. This regulator presents a further impediment to processing power in both directions. Wireless interfaces also tend to be very limited in power, both because of poor coupling efficiency and because of the heat generated by the poor coupling for any appreciable levels of power. The poor coupling efficiency of wireless power systems also produces a loss in the voltage that can be produced by a system component, which causes a mismatch in the voltage that could be wirelessly produced by the battery compared with the voltage necessary to wirelessly charge the battery.
There are many advantages associated with a battery that can be wirelessly charged or discharged, that is, one which interfaces wirelessly over a metallically isolated path for both charging and discharging. What is needed in the art, therefore, is a power system that can wirelessly charge a battery that overcomes the deficiencies in the prior art.